U.S. patent number 9,026,028 [Application Number 13/765,190] was granted by the patent office on 2015-05-05 for image forming apparatus.
This patent grant is currently assigned to Fuji Xerox Co., Ltd.. The grantee listed for this patent is Fuji Xerox Co., Ltd.. Invention is credited to Koji Nishimura.
United States Patent |
9,026,028 |
Nishimura |
May 5, 2015 |
Image forming apparatus
Abstract
An image forming apparatus includes a first image forming unit
that forms an image by using a first toner having a first average
particle diameter, a second image forming unit that forms an image
by using a second toner having a second average particle diameter
that is greater than the first average particle diameter, and a
transport path through which the first and second toners collected
from the first and second image forming units, respectively, are
transported. The transport path is configured such that a position
at which the second toner is collected from the second image
forming unit is located upstream of a position at which the first
toner is collected from the first image forming unit in a
transporting direction of the transport path.
Inventors: |
Nishimura; Koji (Kanagawa,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Fuji Xerox Co., Ltd. |
Minato-ku, Tokyo |
N/A |
JP |
|
|
Assignee: |
Fuji Xerox Co., Ltd. (Tokyo,
JP)
|
Family
ID: |
49946660 |
Appl.
No.: |
13/765,190 |
Filed: |
February 12, 2013 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20140023414 A1 |
Jan 23, 2014 |
|
Foreign Application Priority Data
|
|
|
|
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Jul 20, 2012 [JP] |
|
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2012-161827 |
|
Current U.S.
Class: |
399/358 |
Current CPC
Class: |
G03G
21/105 (20130101); G03G 15/161 (20130101); G03G
2215/0129 (20130101) |
Current International
Class: |
G03G
21/10 (20060101) |
Field of
Search: |
;399/223,231,299 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Curran; Gregory H
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
What is claimed is:
1. An image forming apparatus comprising: a first image forming
unit configured to form an image by using a first toner having a
first average particle diameter; a second image forming unit
configured to form an image by using a second toner having a second
average particle diameter that is greater than the first average
particle diameter; and a transport path configured to transport the
residual first toner and residual second toner collected from the
first and second image forming units, respectively, wherein the
transport path is configured such that a position at which the
residual second toner is collected from the second image forming
unit is located upstream of a position at which the residual first
toner is collected from the first image forming unit in a
transporting direction of the transport path.
2. The image forming apparatus according to claim 1, wherein the
residual first toner comprises excess waste toner leftover from
forming the image by the first image forming unit, and wherein the
residual second toner comprises excess waste toner leftover from
forming the image by the second image forming unit.
3. The image forming apparatus according to claim 1, wherein the
first image forming unit comprises: a first drum cleaning device;
and a first toner collector configured to collect the residual
first toner discharged from the first drum cleaning device, wherein
the second image forming unit comprises: a second drum cleaning
device; and a second toner collector configured to collect the
residual second toner discharged from the second drum cleaning
device, and wherein the transport path is configured to transport
the residual first toner collected by the first toner collector and
the residual second toner collected by the second toner
collector.
4. The image forming apparatus according to claim 1, wherein the
transport path comprises a passage forming member having a
cylindrical inner structure.
5. An image forming apparatus comprising: a first image forming
unit configured to form an image by using a first toner having a
first average particle diameter; a second image forming unit
configured to form an image by using a second toner having a second
average particle diameter that is greater than the first average
particle diameter; an intermediate transfer body configured to have
the images formed by the first and second image forming units
transferred thereon; and a transport path configured to transport
residual first toner and residual second toner collected from the
first and second image forming units and the intermediate transfer
body, wherein the transport path is configured such that a position
at which the residual first toner and the residual second toner are
collected from the intermediate transfer body is located upstream
of positions at which the residual first toner and the residual
second to toner are collected from the first and second image
forming units, respectively, in a transporting direction of the
transport path.
6. The image forming apparatus according to claim 5, wherein the
image forming apparatus has a cleaning mode for cleaning the
transport path, and wherein, in the cleaning mode, a toner image to
be collected is formed by the second image forming unit and
transferred onto the intermediate transfer body, and the second
toner that forms the toner image to be collected that has been
transferred onto the intermediate transfer body is transported
through the transport path.
7. The image forming apparatus according to claim 3, wherein the
first image forming unit comprises: a first developing device; and
a first developer collector configured to collect excess first
developer discharged from the first developing device, wherein the
second image forming unit comprises: a second developing device;
and a second developer collector configured to collect excess
second developer discharged from the second developing device, and
wherein the transport path is configured to transport the excess
first developer collected by the first developer collector and the
excess second developer collected by the second developer
collector.
8. The image forming apparatus according to claim 4, wherein the
transport path comprises a screw auger that extends through the
passage forming member.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based on and claims priority under 35 USC 119
from Japanese Patent Application No. 2012-161827 filed Jul. 20,
2012.
BACKGROUND
1. Technical Field
The present invention relates to an image forming apparatus.
2. Summary
According to an aspect of the invention, there is provided an image
forming apparatus including a first image forming unit that forms
an image by using a first toner having a first average particle
diameter, a second image forming unit that forms an image by using
a second toner having a second average particle diameter that is
greater than the first average particle diameter, and a transport
path through which the first and second toners collected from the
first and second image forming units, respectively, are
transported. The transport path is configured such that a position
at which the second toner is collected from the second image
forming unit is located upstream of a position at which the first
toner is collected from the first image forming unit in a
transporting direction of the transport path.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiments of the present invention will be described in
detail based on the following figures, wherein:
FIG. 1 illustrates the structure of an image forming apparatus
according to a first exemplary embodiment of the present
invention;
FIG. 2 illustrates the structure of a part of the image forming
apparatus according to the first exemplary embodiment of the
present invention;
FIG. 3 illustrates the structure of a collected-toner transporting
device;
FIG. 4 illustrates the structure of a part of the collected-toner
transporting device;
FIG. 5 illustrates the structure of a collected-toner transporting
device included in an image forming apparatus according to a second
exemplary embodiment of the present invention; and
FIG. 6 illustrates the structure of a collected-toner transporting
device included in an image forming apparatus according to a third
exemplary embodiment of the present invention.
DETAILED DESCRIPTION
Exemplary embodiments of the present invention will now be
described with reference to the drawings.
First Exemplary Embodiment
FIGS. 1 and 2 illustrate an image forming apparatus 1 according to
the first exemplary embodiment. FIG. 1 illustrates the overall
structure of the image forming apparatus 1, and FIG. 2 illustrates
an enlarged view of a part (for example, image forming devices) of
the image forming apparatus 1.
Overall Structure of Image Forming Apparatus
The image forming apparatus 1 according to the first exemplary
embodiment is, for example, a color printer. The image forming
apparatus 1 includes plural image forming devices 10, an
intermediate transfer device 20, a paper feeding device 50, and a
fixing device 40. Each image forming device 10 forms a toner image
developed with toner contained in developer 4. The intermediate
transfer device 20 carries toner images formed by the respective
image forming devices 10 and transports the toner images to a
second transfer position at which the toner images are transferred
onto a sheet of recording paper 5, which is an example of a
recording medium, in a second transfer process. The paper feeding
device 50 contains and transports the sheet of recording paper 5 to
be supplied to the second transfer position of the intermediate
transfer device 20. The fixing device 40 fixes the toner images
that have been transferred onto the sheet of recording paper 5 by
the intermediate transfer device 20 in the second transfer
process.
In the case where, for example, an image input device 60 that
inputs a document image to be formed on the sheet of recording
paper 5 is additionally provided, the image forming apparatus 1 may
be configured as a color copier. Referring to FIG. 1, the image
forming apparatus 1 includes a housing 1a including, for example, a
supporting structural member and an external covering part. The
one-dot chain line shows a transport path along which the sheet of
recording paper 5 is transported in the housing 1a. Structure of
Part of Image Forming Apparatus
The image forming devices 10 include six image forming devices 10Y,
10M, 10C, 10K, 10S1, and 10S2. The image forming devices 10Y, 10M,
10C, and 10K respectively form toner images of four colors, which
are yellow (Y), magenta (M), cyan (C), and black (K). The image
forming devices 10S1 and 10S2 respectively form two types of toner
images of special colors S1 and S2. The six image forming devices
10 (S1, S2, Y, M, C, and K) are arranged along a line in the inner
space of the housing 1a. The developers 4 (S1 and S2) of the
special colors (S1 and S2) contain, for example, materials of
colors which are difficult or impossible to be expressed by the
above-described four colors. More specifically, toners of colors
other than the four colors, toners having the same colors as the
four colors but saturations different from those of the toners of
four colors, clear toners that increase the glossiness, foaming
toners used in Braille printing, fluorescent toners, etc., may be
used. The image forming devices 10 (S1, S2, Y, M, C, and K) have a
substantially similar structure, as described below, except for the
type of the developer used therein.
As illustrated in FIGS. 1 and 2, each image forming device 10 (S1,
S2, Y, M, C, or K) includes a photoconductor drum 11 that rotates,
and devices described below are arranged around the photoconductor
drum 11. The devices include a charging device 12, an exposure
device 13, a developing device 14 (S1, S2, Y, M, C, K), a first
transfer device 15, a pre-cleaning charging device 16, a drum
cleaning device 17, and a electricity removing device 18. The
charging device 12 charges a peripheral surface (image carrying
surface) of the photoconductor drum 11, on which an image may be
formed, to a certain potential. The exposure device 13 irradiates
the charged peripheral surface of the photoconductor drum 11 with
light LB based on image information (signal) to form an
electrostatic latent image (for the corresponding color) having a
potential difference. The developing device 14 (S1, S2, Y, M, C, or
K) forms a toner image by developing the electrostatic latent image
with toner contained in the developer 4 of the corresponding color
(S1, S2, Y, M, C, or K). The first transfer device 15 performs a
first transfer process in which the toner image is transferred onto
the intermediate transfer device 20. The pre-cleaning charging
device 16 charges substances, such as toner, that remain on the
image carrying surface of the photoconductor drum 11 after the
first transfer process. The drum cleaning device 17 cleans the
image carrying surface by removing the recharged substances. The
electricity removing device 18 removes electricity from the image
carrying surface of the photoconductor drum 11 after the cleaning
process.
The photoconductor drum 11 includes a cylindrical or columnar base
member that is grounded and a photoconductive layer (photosensitive
layer) that is provided on the peripheral surface of the base
member. The photoconductive layer is made of a photosensitive
material and is provided with the image carrying surface. The
photoconductor drum 11 is supported so as to be capable of rotating
in the direction shown by arrow A when power is transmitted thereto
from a rotation driving device (not shown).
The charging device 12 is a non-contact charging device, such as a
corona discharger, and is arranged without contacting the
photoconductor drum 11. The charging device 12 includes a discharge
member that receives a charging voltage. In the case where the
developing device 14 performs reversal development, a voltage or
current having the same polarity as the charging polarity of the
toner supplied by the developing device 14 is supplied as the
charging voltage.
The exposure device 13 forms the electrostatic latent image by
irradiating the charged peripheral surface of the photoconductor
drum 11 with light (arrowed dashed line) LB generated in accordance
with the image information input to the image forming apparatus 1.
When forming the electrostatic latent image, the exposure device 13
receives the image information (signal) that is input to the image
forming apparatus 1 by any method.
As illustrated in FIG. 2, each developing device 14 (S1, S2, Y, M,
C, or K) includes a housing 140 having an opening and a chamber of
the developer 4. Two developing rollers 141 and 142, two
stirring-and-transporting members 143 and 144, and a
layer-thickness regulating member 145 are disposed in the housing
140. The two developing rollers 141 and 142 hold the developer 4
and transport the developer 4 to respective developing areas in
which the developing rollers 141 and 142 face the photoconductor
drum 11. The stirring-and-transporting members 143 and 144 are, for
example, two screw augers that transport the developer 4 while
stirring the developer 4 so that the developer 4 is moved along the
developing roller 141. The layer-thickness regulating member 145
regulates the amount (layer thickness) of the developer 4 held by
the developing roller 141. A developing voltage supplied from a
power supply device (not shown) is applied between the
photoconductor drum 11 and the developing rollers 141 and 142 of
the developing device 14. The developing rollers 141 and 142 and
the stirring-and-transporting members 143 and 144 receive power
from a rotation driving device (not shown) and rotates in a certain
direction. Two-component developers containing nonmagnetic toner
and magnetic carrier are used as the developers 4 (Y, M, C, and K)
of the above-described four colors and the developers 4 (S1 and S2)
of the two special colors.
The first transfer device 15 is a contact transfer device including
a first transfer roller which rotates while contacting the
peripheral surface of the photoconductor drum 11 and receives a
first transfer voltage. A direct-current voltage having a polarity
opposite to the charging polarity of the toner is supplied as the
first transfer voltage from the power supply device (not
shown).
As illustrated in FIG. 2, the drum cleaning device 17 includes a
container-shaped body 170 that has an opening, a cleaning plate
171, a rotating brush roller 172, and a transporting member 173.
The cleaning plate 171 is arranged to contact the peripheral
surface of the photoconductor drum 11 at a certain pressure after
the first transfer process and clean the peripheral surface of the
photoconductor drum 11 by removing substances such as residual
toner therefrom. The rotating brush roller 172 is arranged to
contact with the peripheral surface of the photoconductor drum 11
while rotating at a position upstream of the cleaning plate 171 in
the rotation direction of the photoconductor drum 11. The
transporting member 173 is, for example, a screw auger that
transports the substances such as toner that have been removed by
the cleaning plate 171 to a collecting system (not shown). The
cleaning plate 171 may be formed of a plate-shaped member (for
example, a blade) made of rubber or the like.
As illustrated in FIG. 1, the intermediate transfer device 20 is
disposed below the image forming devices 10 (S1, S2, Y, M, C, and
K). The intermediate transfer device 20 basically includes an
intermediate transfer belt 21, plural belt support rollers 22 to
27, a second transfer device 30, and a belt cleaning device 28. The
intermediate transfer belt 21 rotates in the direction shown by
arrow B while passing through a first transfer position, which is
between the photoconductor drum 11 and the first transfer device 15
(first transfer roller). The belt support rollers 22 to 27 retain
the intermediate transfer belt 21 in a desired position at the
inner surface of the intermediate transfer belt 21 so that the
intermediate transfer belt 21 is rotatably supported. The second
transfer device 30 is disposed to oppose the belt support roller 26
that supports the intermediate transfer belt 21 at the
outer-peripheral-surface (image-carrying-surface) side of the
intermediate transfer belt 21. The second transfer device 30
performs a second transfer process in which the toner images on the
intermediate transfer belt 21 are transferred onto the sheet of
recording paper 5. The belt cleaning device 28 cleans the outer
peripheral surface of the intermediate transfer belt 21 by removing
substances such as toner and paper dust that remain on the outer
peripheral surface of the intermediate transfer belt 21 after the
intermediate transfer belt 21 has passed the second transfer device
30.
The intermediate transfer belt 21 may be, for example, an endless
belt made of a material obtained by dispersing a resistance
adjusting agent, such as carbon black, in a synthetic resin, such
as polyimide resin or polyamide resin. The belt support roller 22
serves as a driving roller. The belt support rollers 23, 25, and 27
serve as driven rollers for retaining the position of the
intermediate transfer belt 21. The belt support roller 24 serves as
a tension-applying roller. The belt support roller 26 serves as a
back-up roller in the second transfer process.
As illustrated in FIG. 1, the second transfer device 30 includes a
second transfer belt 31 and plural support rollers 32 to 36. The
second transfer belt 31 rotates in the direction shown by arrow C
while passing through a second transfer position, which is on the
outer-peripheral-surface side of the intermediate transfer belt 21
that is supported by the belt support roller 26 in the intermediate
transfer device 20. The support rollers 32 to 36 retain the second
transfer belt 31 in a desired position at the inner surface of the
second transfer belt 31 so that the second transfer belt 31 is
rotatably supported. The second transfer belt 31 is, for example,
an endless belt having substantially the same structure as that of
the above-described intermediate transfer belt 21. The belt support
roller 32 is arranged so that the second transfer belt 31 is
pressed at a certain pressure against the outer peripheral surface
of the intermediate transfer belt 21 supported by the belt support
roller 26. The belt support roller 32 serves as a driving roller,
and the belt support roller 36 serves as a tension-applying roller.
The belt support roller 32 of the second transfer device 30 or the
belt support roller 26 of the intermediate transfer device 20
receives a direct-current voltage having a polarity that is
opposite to or the same as the charging polarity of the toner as a
second transfer voltage.
The fixing device 40 includes a heating rotating body 42 and a
pressing rotating body 43 that are arranged in a housing 41 having
an inlet and an outlet for the sheet of recording paper 5. The
heating rotating body 42 includes a fixing belt that rotates in the
direction shown by the arrow and that is heated by a heater so that
the surface temperature thereof is maintained at a predetermined
temperature. The pressing rotating body 43 is drum-shaped and
contacts the heating rotating body 42 at a certain pressure
substantially along the axial direction of the heating rotating
body 42, so that the pressing rotating body 43 is rotated. In the
fixing device 40, the contact portion in which the heating rotating
body 42 and the pressing rotating body 43 contact each other serves
as a fixing process unit that performs a certain fixing process
(heating and pressing).
The paper feeding device 50 is disposed below the intermediate
transfer device 20 and the second transfer device 30. The paper
feeding device 50 basically includes at least one paper container
51 that contains sheets of recording paper 5 of the desired size,
type, etc., in a stacked manner and a transporting device 52 that
feeds the sheets of recording paper 5 one at a time from the paper
container 51. The paper container 51 is, for example, attached to
the housing 1a such that the paper container 51 may be pulled out
therefrom at the front side (side that faces the user during
operation) of the housing 1a.
Plural pairs of paper transport rollers 53 to 57, which transport
each of the sheets of recording paper 5 fed from the paper feeding
device 50 to the second transfer position, and a paper transport
path including transport guide members (not shown) are provided
between the paper feeding device 50 and the second transfer device
30. The pair of paper transport rollers 57 that are disposed
immediately in front of the second transfer position on the paper
transport path serve as, for example, registration rollers for
adjusting the time at which each sheet of recording paper 5 is to
be transported. A paper transport device 58, which may be
belt-shaped, is provided between the second transfer device 30 and
the fixing device 40. The paper transport device 58 transports the
sheet of recording paper 5 that has been transported from the
second transfer belt 31 of the second transfer device 30 after the
second transfer process to the fixing device 40. A pair of paper
discharge rollers 59 are disposed near a paper outlet formed in the
housing 1a. The pair of paper discharge rollers 59 discharge the
sheet of recording paper 5 that has been subjected to the fixing
process and transported from the fixing device 40 to the outside of
the housing 1a.
The image input device 60, which is provided when the image forming
apparatus 1 is formed as a color copier, is an image reading device
that reads an image of a document 6 having the image information to
be printed. The image input device 60 is arranged, for example,
above the housing 1a as illustrated in FIG. 1. The image input
device 60 basically includes a document receiving plate (platen
glass) 61, a light source 62, a reflection mirror 63, a first
reflection mirror 64, a second reflection mirror 65, an image
reading element 66, and an imaging lens 67. The document receiving
plate 61 includes, for example, a transparent glass plate on which
the document 6 having the image information to be read is placed.
The light source 62 irradiates the document 6 placed on the
document receiving plate 61 while moving. The reflection mirror 63
receives reflected light from the document 6 and reflects the light
in a predetermined direction while moving together with the light
source 62. The first and second reflection mirrors 64 and 65 move
at a predetermined speed by a predetermined distance with respect
to the reflection mirror 63. The image reading element 66 includes,
for example, a charge coupled device (CCD) that receives and reads
the reflected light from the document 6 and converts the reflected
light into an electrical signal. The imaging lens 67 focuses the
reflected light on the image reading element 66. Referring to FIG.
1, the document receiving plate 61 is covered by an opening-closing
covering part 68.
The image information of the document 6 that has been read by the
image input device 60 is input to an image processing device 70,
which subjects the image information to necessary image processing.
The image input device 60 transmits the read image information of
the document 6 to the image processing device 70 as, for example,
red (R), green (G), and blue (B) three-color image data (for
example, 8-bit data for each color). The image processing device 70
subjects the image data transmitted from the image input device 60
to predetermined image processing, such as shading correction,
misregistration correction, brightness/color space conversion,
gamma correction, frame erasing, and color/movement edition. The
image processing device 70 converts the image signals obtained as a
result of the image processing into image signals of the
above-described four colors (Y, M, C, and K), and transmits the
image signals to the exposure device 13. The image processing
device 70 also generates image signals for the two special colors
(S1 and S2).
Operation of Image Forming Apparatus
A basic image forming operation performed by the image forming
apparatus 1 will now be described.
First, an image forming operation for forming a full-color image by
combining toner images of four colors (Y, M, C, and K) by using the
four image forming devices 10 (Y, M, C, and K) will be
described.
When the image forming apparatus 1 receives command information of
a request for the image forming operation (printing), the four
image forming devices 10 (Y, M, C, and K), the intermediate
transfer device 20, the second transfer device 30, and the fixing
device 40 are activated.
In each of the image forming devices 10 (Y, M, C, and K), first,
the photoconductor drum 11 rotates in the direction shown by arrow
A and the charging device 12 charges the surface of the
photoconductor drum 11 to a certain potential with a certain
polarity (negative polarity in the first exemplary embodiment).
Subsequently, the exposure device 13 irradiates the charged surface
of the photoconductor drum 11 with the light LB based on the image
signal obtained by converting the image information input to the
image forming apparatus 1 into a component of the corresponding
color (Y, M, C, or K). As a result, an electrostatic latent image
for the corresponding color having a certain potential difference
is formed on the surface of the photoconductor drum 11.
After that, each of the developing devices 14 (Y, M, C, and K)
supplies the toner of the corresponding color (Y, M, C, or K),
charged with a certain polarity (negative polarity), from the
developing rollers 141 and 142 to the electrostatic latent image of
the corresponding color formed on the photoconductor drum 11. The
toner electrostatically adheres to the electrostatic latent image,
so that the electrostatic latent image is developed. As a result of
the developing process, the electrostatic latent images for the
respective colors formed on the photoconductor drums 11 are
visualized as toner images of the four colors (Y, M, C, and K)
developed with the toners of the respective colors.
When the toner images of the respective colors formed on the
photoconductor drums 11 of the image forming devices 10 (Y, M, C,
and K) reach the respective first transfer positions, the first
transfer devices 15 perform the first transfer process so that the
toner images of the respective colors are successively transferred,
in a superimposed manner, onto the intermediate transfer belt 21 of
the intermediate transfer device 20 that rotates in the direction
of arrow B.
In each image forming device 10, after the first transfer process,
the pre-cleaning charging device 16 recharges the substances, such
as toner, that remain on the surface of the photoconductor drum 11
after the first transfer process. Subsequently, the drum cleaning
device 17 cleans the surface of the photoconductor drum 11 by
scraping off the recharged substances, and the electricity removing
device 18 removes the electricity from the cleaned surface of the
photoconductor drum 11. Thus, the image forming device 10 is set to
a standby state for the next image forming process.
In the intermediate transfer device 20, the intermediate transfer
belt 21 rotates so as to transport the toner images that have been
transferred onto the intermediate transfer belt 21 by the first
transfer process to the second transfer position. The paper feeding
device 50 feeds a sheet of recording paper 5 to the paper transport
path in accordance with the image forming process. In the paper
transport path, the pair of paper transport rollers 57, which serve
as registration rollers, transport the sheet of recording paper 5
to the second transfer position in accordance with the transfer
timing.
At the second transfer position, the second transfer device 30
performs the second transfer process in which the toner images on
the intermediate transfer belt 21 are simultaneously transferred
onto the sheet of recording paper 5. In the intermediate transfer
device 20 after the second transfer process, the belt cleaning
device 28 cleans the surface of the intermediate transfer belt 21
by removing the substances, such as toner, that remain on the
surface after the second transfer process.
The sheet of recording paper 5, onto which the toner images have
been transferred by the second transfer process, is released from
the intermediate transfer belt 21 and from the second transfer belt
31 and transported to the fixing device 40 by the paper transport
device 58. In the fixing device 40, the sheet of recording paper 5
after the second transfer process is guided through the contact
portion between the heating rotating body 42 and the pressing
rotating body 43 that rotate. Thus, a fixing process (heating and
pressing) is performed so that the unfixed toner images are fixed
to the sheet of recording paper 5. In the case where the image
forming operation is performed to form an image only on one side of
the sheet of recording paper 5, the sheet of recording paper 5 that
has been subjected to the fixing process is discharged to, for
example, a discharge container (not illustrated) disposed outside
the housing 1a by the paper discharge rollers 59.
As a result of the above-described operation, the sheet of
recording paper 5 on which a full-color image is formed by
combining toner images of four colors is output.
Next, the case will be described in which special-color toner
images are additionally formed by using the developers of the
special colors S1 and S2 in the above-described normal image
forming operation performed by the image forming apparatus 1.
In this case, first, the image forming devices 10S1 and 10S2
perform an operation similar to the image forming process performed
by the image forming devices 10 (Y, M, C, and K). Accordingly,
special-color toner images (S1 and S2) are formed on the
photoconductor drums 11 of the image forming devices 10S1 and 10S2.
Subsequently, similar to the manner in which the toner images of
the four colors are processed in the above-described image forming
operation, the special-color toner images formed by the image
forming devices 10S1 and 10S2 are transferred onto the intermediate
transfer belt 21 of the intermediate transfer device 20 in the
first transfer process. Then, in the second transfer process, the
second transfer device 30 transfers the special-color toner images
from the intermediate transfer belt 21 onto the sheet of recording
paper 5 together with the toner images of the other colors. Lastly,
the sheet of recording paper 5, onto which the special-color toner
images and the toner images of the other colors have been
transferred in the second transfer process, is subjected to the
fixing process performed by the fixing device 40 and discharged to
the outside of the housing 1a.
As a result of the above-described operation, the sheet of
recording paper 5 is output on which the two special-color toner
images overlap with a part or the entirety of the full-color image
formed by combining the toner images of four colors together.
In the case where the image forming apparatus 1 is equipped with
the image input device 60 and serves as a color copier, a basic
image forming operation is performed as follows.
That is, in this case, when the document 6 is set to the image
input device 60 and command information of a request for the image
forming operation (copying) is input, the image input device 60
reads the document image from the document 6. The information of
the read document image is subjected to the above-described image
processing performed by the image processing device 70, so that the
image signals are generated. The image signals are transmitted to
the exposure devices 13 of the image forming devices 10 (S1, S2, Y,
M, C, and K). Accordingly, each image forming device 10 forms an
electrostatic latent image and a toner image based on the image
information of the document 6. After that, an operation similar to
the above-described image forming operation (printing) is performed
and the sheet of recording paper 5 on which an image obtained by
combining the toner images together is formed is output.
Toner Used in Image Forming Device
In the present exemplary embodiment, yellow (Y), magenta (M), cyan
(C), and black (K) image forming devices 10 (Y, M, C, and K) use
toners having relatively small particle diameters (number-average
particle diameters), e.g., about 5 to 6 .mu.m, to comply with high
image quality requirements. The image forming devices 10S1 and 10S2
that form toner images of special colors S1 and S2 use, for
example, clear toners or foaming toners for Braille printing. The
clear toners and foaming toners for Braille printing have
relatively large particle diameters (number-average particle
diameters) which are, for example, about 10 to 40 .mu.m. In the
present exemplary embodiment, it is assumed that the image forming
device 10S1 uses a clear toner and the image forming device 10S2
uses a foaming toner for Braille printing.
Structure of Collected-Toner Transporting Device
FIG. 3 illustrates the structure of a collected-toner transporting
device 80 included in the image forming apparatus. The
collected-toner transporting device 80 is disposed on the back side
of the housing 1a of the image forming apparatus 1, and FIG. 3 is a
rear view of the image forming apparatus.
Each of the image forming devices 10 (S1, S2, Y, M, C, and K)
includes a developer collector 81 that receives excess developer
discharged from the developing device 14 and a toner collector 82
that receives substances such as residual toner discharged from the
drum cleaning device 17. A collecting transport member (not shown)
is provided at an end of one of the stirring-and-transporting
members 143 and 144 of the developing device 14. The collecting
transport member extends to the back side of the image forming
apparatus 1 and collects the excess developer in the developer
collector 81. The transporting member 173, such as a screw auger,
of the cleaning device 17 extends to the back side of the image
forming apparatus 1 and collects the substances such as the
collected toner in the toner collector 82.
A horizontal transport unit 83, which forms a transport path of the
collected-toner transporting device 80, extends below the developer
collectors 81 and the toner collectors 82 of the image forming
devices 10 (S1, S2, Y, M, C, and K) from the position below the
special-color (S1) developer collector 81S1 to the position below
the black (K) toner collector 82K. The horizontal transport unit 83
includes at least a passage forming member 84 having a cylindrical
inner structure and a transporting member 85, such as a screw
auger, that extends through the passage forming member 84 over the
entire length of the passage forming member 84. The transporting
member 85 is rotated through a gear (not shown) by a drive motor
106 provided at an end of the transporting member 85 near the
special-color (S1) developer collector 81S1. The transporting
direction of the transporting member 85 is set so that the
special-color (S1) developer collector 81S1 is located at the
upstream side and the black (K) toner collector 82K is located at
the downstream side.
The passage forming member 84 is connected to the bottom ends of
the developer collectors 81 and the toner collectors 82, and the
excess developers collected by the developer collectors 81 and the
substances such as residual toners collected by the toner
collectors 82 are introduced into the passage forming member 84.
The passage forming member 84 includes support members 86 at
positions corresponding to the toner collectors 82. The support
members 86 support cylindrical bottom end portions 82a of the toner
collectors 82. The toner collectors 82 include cylindrical portions
82b in which helical agitators or the like that assist downward
movement of the toners may be disposed.
The developer collectors 81 include tubular members 87 that are
connected to the cylindrical portions 82b of the toner collectors
82 at intermediate positions of the cylindrical portions 82b, and
the developers are collected through the toner collectors 82.
As illustrated in FIG. 4, the special-color (S1) developer
collector 81S1 is connected to the passage forming member 84 at a
position adjacent to an end 29a of a transporting member 29, such
as a screw auger, that transports substances such as residual
toners collected by the belt cleaning device 28 of the intermediate
transfer belt 21 toward the back side of the housing 1a of the
image forming apparatus 1.
As illustrated in FIG. 3, the downstream end of the horizontal
transport unit 83 in the transporting direction is connected to a
dropping transport unit 88 through which the collected substances
transported by the horizontal transport unit 83 are caused to fall
in the direction of gravity. The dropping transport unit 88
includes a cylindrical passage forming member 89 and a transporting
member 90, such as a helical agitator, disposed in the passage
forming member 89. The transporting member 90 is rotated by a drive
motor 91. The passage forming member 89 includes an upper portion
89a that is tapered such that the diameter thereof decreases toward
the bottom and a lower portion 89b having a cylindrical shape with
a uniform diameter.
The bottom end of the dropping transport unit 88 is connected to a
final transport unit that transports the collected substances
transported by the dropping transport unit 88 to large-capacity
containers 92 and 93 that are arranged next to each other. The
final transport unit includes a first transport unit 94 and a
second transport unit 95. Among the two containers 92 and 93 that
are arranged next to each other, the first transport unit 94
transports the collected substances to the upstream container 92
and the second transport unit 95 transports the collected
substances that have been transported to the upstream container 92
by the first transport unit 94 to the downstream container 93. The
first and second transport units 94 and 95 respectively include at
least passage forming members 96 and 97 having cylindrical inner
structures and transporting members 98 and 99, such as screw
augers, that extend through the passage forming members 96 and 97.
The transporting members 98 and 99 are respectively rotated by
drive motors 100 and 101. When the container 92 becomes full, the
collected substances are transported to the other container 93 by
the first and second transport units 94 and 95.
Operation of Collected-Toner Transporting Device
At a predetermined operation time, such as when the image forming
operation is completed or when a predetermined number of sheets
have been subjected to printing, the horizontal transport unit 83,
the dropping transport unit 88, and the final transport unit of the
collected-toner transporting device 80 are activated. Accordingly,
the collected substances including the excess developers collected
by the developer collectors 81 and substances such as residual
toners collected by the toner collectors 82 are transported through
the horizontal transport unit 83, the dropping transport unit 88,
and the final transport unit and collected in the container 92 or
93.
The special-color (S1) image forming device 10S1, which uses a
toner having a relatively large particle diameter, is located at a
most upstream position along the horizontal transport unit 83, and
the special-color (S2) image forming device 10S2, which also uses a
toner having a relatively large particle diameter, is located on
the downstream side of the special-color (S1) image forming device
10S1.
When the collected-toner transporting device 80 is activated, in
the yellow (Y), magenta (M), cyan (C), and black (K) image forming
devices 10 (Y, M, C, and K), which use toners having relatively
small particle diameters, the toners easily adhere to wall surfaces
of the passage forming members 84, 89, 96, and 97 and the
transporting members 85, 90, 98, and 99 included in the horizontal
transport unit 83, the dropping transport unit 88, and the final
transport unit owing to the small diameters thereof. Therefore,
there is a risk that clogging will occur.
In the present exemplary embodiment, the developer collectors 81
and the toner collectors 82 that collect the substances from the
special-color (S1) and special-color (S2) image forming devices
10S1 and 10S2, which use the toners having relatively large
particle diameters, are arranged in an upstream region of the
horizontal transport unit 83. Therefore, the toners having
relatively large particle diameters are collected through the
developer collectors 81 and the toner collectors 82 arranged in the
upstream region of the horizontal transport unit 83, and are
transported through the passage forming members. The toners having
relatively large particle diameters have relatively large volumes,
and do not easily adhere to the transporting members. The toners
having relatively large particle diameters are transported while
receiving a transporting force applied by the transporting members,
and are therefore capable of removing the toners having relatively
small particle diameters that have adhered to the wall surfaces of
the passage forming members and the transporting members. As a
result, the occurrence of toner clogging at the passage forming
members and the transporting members in the horizontal transport
unit 83, the dropping transport unit 88, and the final transport
unit may be reduced.
Second Exemplary Embodiment
FIG. 5 illustrates an image forming apparatus according to a second
exemplary embodiment of the present invention. Components similar
to those in the above-described first exemplary embodiment are
denoted by the same reference numerals. In the second exemplary
embodiment, a toner having a relatively large particle diameter is
used in an image forming device positioned at an end of a
horizontal transport unit, and a transport path of a
collected-toner transporting device is set so that the image
forming device that uses the toner having a relatively large
particle diameter is at an upstream position in a toner collecting
direction.
Specifically, in the second exemplary embodiment, a black (K) image
forming device 10K, which is disposed at the right end in FIG. 5,
uses black (K) toner having a relatively large particle diameter.
The black (K) toner has a relatively large particle diameter
(number-average particle diameter) which are, for example, about 10
to 20 .mu.m.
Special-color (S1) and special-color (S2) image forming devices
10S1 and 10S2, for example, use toners having the same colors as
magenta (M) and cyan (C) toners but having saturations different
from those of the magenta (M) and cyan (C) toners. To increase the
image quality, the toners having the same colors as the magenta (M)
and cyan (C) toners but having saturations different from those of
the magenta (M) and cyan (C) toners have relatively small particle
diameters, similar to the magenta (M) and cyan (C) toners.
Structure of Collected-Toner Transporting Device
FIG. 5 illustrates the structure of a collected-toner transporting
device 80 included in the image forming apparatus according to the
second exemplary embodiment.
A horizontal transport unit 83 is configured such that a
transporting member 85 disposed in a passage forming member 84
transports collected substances, such as residual toners, so that
the black (K) image forming device 10K is at the most upstream
position and the special-color (S1) image forming device 10S1 is at
a downstream position. The transporting member 85 is rotated by a
drive motor 106 arranged at an end of the transporting member 85
near the black (K) image forming device 10K.
In the present exemplary embodiment, a dropping transport unit 88
is disposed between a developer collector 81S1 and a toner
collector 82S1 of the special-color (S1) image forming device 10S1.
The excess developer from the developer collector 81S1 of the
special-color (S1) image forming device 10S1 is transported to the
dropping transport unit 88 in the same direction as that in the
first exemplary embodiment.
Thus, also in the second exemplary embodiment, the toner collector
82K that collects the toner having a relatively large particle
diameter is disposed at an upstream position. Therefore, similar to
the first exemplary embodiment, the occurrence of toner clogging at
the passage forming members and the transporting members in the
horizontal transport unit 83, the dropping transport unit 88, and
the final transport unit may be reduced.
Other structures and operations are similar to those in the first
exemplary embodiment, and explanations thereof are thus
omitted.
Third Exemplary Embodiment
FIG. 6 illustrates an image forming apparatus according to a third
exemplary embodiment of the present invention. Components similar
to those in the above-described exemplary embodiments are denoted
by the same reference numerals. In the third exemplary embodiment,
a cleaning mode for cleaning a transport path of a transporting
device is provided. In the cleaning mode, a toner image to be
collected is formed by using a toner having a relatively large
particle diameter, and is collected by a toner collecting unit
located at an upstream position in the transporting direction of
the collected toners.
In the third exemplary embodiment, as illustrated in FIG. 6, among
special-color (S1), special-color (S2), yellow (Y), magenta (M),
cyan (C), and black (K) image forming devices 10 (S1, S2, Y, M, C,
and K) arranged along a line, the image forming device 10K that
uses a black (K) toner, which has a relatively large particle
diameter, is disposed at the most downstream position of a
horizontal transport unit 83 of a collected-toner transporting
device 80 in the toner collecting direction. The special-color (S1)
and special-color (S2) image forming devices 10S1 and 10S2 use
toners having relatively small particle diameters.
In the present exemplary embodiment, the collected-toner
transporting device 80 has a cleaning mode for cleaning the
transport path of, for example, the horizontal transport unit 83.
In the cleaning mode, a toner band formed of a band-shaped tone
image is formed on the photoconductor drum 11 by the image forming
device 10K that uses the black (K) toner, which has a relatively
large particle diameter. The toner band formed on the
photoconductor drum 11 is transferred onto the intermediate
transfer belt 21. Then, the polarity of the second transfer unit is
switched so that the toner band passes through the second transfer
unit and is collected by the belt cleaning device 28 that removes
the substances such as toners from the intermediate transfer belt
21.
The toners collected by the belt cleaning device 28 is guided into
a passage forming member 84 included in the horizontal transport
unit 83 at a position downstream of a developer collector 81 of the
special-color (S1) image forming device 10S1, which is located at
the most upstream position, as illustrated in FIGS. 4 and 6.
Thus, in the third exemplary embodiment, the black (K) toner, which
has a relatively large particle diameter, may be transported from
the upstream region of the horizontal transport unit 83 in the
cleaning mode. As a result, clogging of the passage forming member
84 may be suppressed owing to the black (K) toner, which has a
relatively large particle diameter, collected from the upstream
region of the passage forming member 84 of the horizontal transport
unit 83.
Other structures and operations are similar to those in the first
exemplary embodiment, and explanations thereof are thus
omitted.
The foregoing description of the exemplary embodiments of the
present invention has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the invention to the precise forms disclosed.
Obviously, many modifications and variations will be apparent to
practitioners skilled in the art. The embodiments were chosen and
described in order to best explain the principles of the invention
and its practical applications, thereby enabling others skilled in
the art to understand the invention for various embodiments and
with the various modifications as are suited to the particular use
contemplated. It is intended that the scope of the invention be
defined by the following claims and their equivalents.
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